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What are brute force attacks?

Read our blog to find out what brute force attacks are, how they work, why they’re dangerous and how to identify, recover from and prevent them.

brute force attack

Among the many types of digital threats, brute force attacks stand out for their simplicity, yet they have the potential to be devastating. When successful, these relentless attempts to crack your password, often dismissed due to their lack of subtlety, can lead to severe consequences.

In this guide, we’ll be looking at:

  • What is a brute force attack?
  • How do brute force attacks work?
  • Different types of brute force attacks
  • Why are brute force attacks dangerous?
  • Real-life examples of brute force attacks
  • How to identify a brute force attack
  • What to do if you’re victim of a brute force attack
  • How to protect against brute force attacks
  • FAQs
  • Conclusion

What is a brute force attack?

Put simply, a brute force attack is a trial-and-error method used by cybercriminals to gain unauthorized access to information. These attacks relentlessly probe by applying a combination of methods until they find a match for an account, a network, or any system secured by a secret, such as a password or token.

How do brute force attacks work?

Brute force attacks utilize exhaustive guessing to crack passwords. Cybercriminals can employ software that bombards a system with an array of potential passwords, systematically cycling through combinations until it stumbles upon the correct one.

Different types of brute force attacks

Brute force attacks can come in various forms, each with its unique approach. These variations are designed to exploit different system vulnerabilities or to optimize the efficiency of the attack. 

Simple brute force attacks

The quintessential form of brute force attack, this technique involves attempting all possible password combinations. It’s a laborious and time-consuming process, but its potential for success increases when passwords are short or lack complexity.

Dictionary attacks

Contrary to its simple counterpart, dictionary attacks leverage a predetermined list of words, similar to a literal dictionary. Recognizing that many people use common words, phrases, or predictable password patterns, cybercriminals employ this method to exploit such habits.

Hybrid brute force attacks

A sophisticated blend of the above methods, hybrid attacks use dictionary words but add numeral or symbol permutations to the mix. So a password such as ‘password1’ or ‘password$’ could be vulnerable to a hybrid attack.

Reverse brute force attacks

In reverse attacks, the attacker has a known password (possibly common or previously leaked) and tries it against a multitude of usernames. So, obviously, the likelihood of finding a match increases with the breadth of usernames tried.

Credential stuffing

This method utilizes previously breached username/password combinations, operating on the assumption that many people reuse passwords across different platforms. The attacker will ‘stuff’ these login credentials into various websites hoping for a match.

Password spraying

Unlike traditional brute force attacks that target a single account, password spraying involves the attacker using a few commonly used passwords against a large number of accounts, minimizing the risk of triggering account lockouts.

Why are brute force attacks dangerous?

Brute force attacks are far more than just an annoyance. They pose serious threats to personal and organizational cybersecurity.

Secrets like your passwords and tokens are essentially the keys to your castle and it only takes one weak password for a brute force attack to be successful. Those who believe that they’re defending against these fall into the trap of thinking that brute force attacks won’t happen if they have one strong password.

However, malicious actors are far more sophisticated and clever than people think.

Cybercriminals may exploit these tactics to pilfer sensitive data, hijack systems for nefarious activities, spread malware, or even ruin an individual’s or an organization’s reputation. The aftermath of such an attack can be daunting, involving costly rectifications and long-term damage control.

Real-life examples of brute force attacks

Understanding brute force attacks takes on a whole new dimension when we examine them in action. Let’s look at some notable instances that highlight the real-world implications of these cyber threats.

In 2012, LinkedIn suffered a significant breach when cybercriminals successfully employed a brute force attack, resulting in the theft of nearly 6.5m user passwords. 

Spotify was subjected to a credential stuffing attack in 2020 which led to the compromise of more than 350,000 accounts. Hackers used a database of 380m records containing login credentials and personal information to gain unauthorized access to accounts.

Also in 2020, over 2000 Magento online stores were the victims of a large-scale automated hacking campaign. The attackers used brute force attacks to gain control of the administrative panel, after which they injected malicious scripts that scraped checkout pages for customer card data.

During the early days of the COVID-19 pandemic, when the use of Zoom grew exponentially, the platform saw a surge in ‘zoom-bombing’ incidents. Unauthorized users employed automated tools to generate meeting IDs via brute force, then disrupted meetings with inappropriate content.

How to identify a brute force attack

Identifying a brute force attack often involves observing patterns and anomalies in system activity. Here are some potential red flags.

Increased login attempts

A sudden surge in login attempts, especially on a single account or across multiple accounts, could indicate a brute force attack. The attacker’s software will typically cycle through thousands or even millions of combinations, leading to a noticeable spike in activity.

Failed login attempts

Concurrent with the increased login attempts, you’ll likely see a significant uptick in failed login attempts. While occasional forgotten passwords are commonplace, an unusually high rate of failures could indicate a brute force attack.

Slow system or network performance

A brute force attack often involves a large volume of data being sent to a system in quick succession. This sudden load can lead to slowed system or network performance. If users or administrators notice inexplicable slowdowns, a brute force attack could be in progress.

Blocked IP addresses

Many systems automatically block IP addresses after a certain number of failed login attempts to thwart brute force attacks. If you notice a sudden increase in blocked IPs, it may suggest an ongoing attack.

Unusual account lockouts

Most systems implement a security feature that locks an account after a set number of unsuccessful login attempts. If users start reporting unexplained lockouts, it could be due to a brute force attack.

Unexpected audit logs

System or event logs can provide valuable insights. Any unexpected or unusual patterns, such as login attempts at odd hours or from unfamiliar locations, should be investigated.

Vigilant monitoring of the above signs, coupled with strong security practices, can assist in identifying a brute force attack at its early stages.

What to do if you’re victim of a brute force attack

If you suspect you’ve been targeted by a brute force attack, take these immediate steps.

Change your password

The first step is to change your password, ideally to something long and complex to deter further brute force attempts.

Enable multi-factor authentication (MFA)

Multi-factor authentication (MFA) adds an additional layer of security beyond just a password to prevent or mitigate the effectiveness of brute force attacks. MFA requires users to provide two or more different types of authentication factors before they can access their accounts

Scan for malware

If an attacker had access to your account or system, they might have installed malware. Run a thorough scan using a reliable antivirus program to find and remove any potential threats.

Report the attack

Inform the relevant authorities about the incident and provide them with as much information as possible. Also, report the breach to your service provider as they may be able to offer additional assistance or advice.

How to protect against brute force attacks

While the consequences of a brute force attack can be severe, there are steps you can take to mitigate the risks.

Adopt strong password policies

Encourage the use of complex, unique passwords. The longer and more intricate the password, the harder it is to crack via brute force.

Implement lockout policies

Locking out an account after a certain number of failed login attempts can deter brute force attacks.

Rate limiting

Rate limiting is employed to safeguard against brute force attacks by restricting the number of login or resource access attempts within a defined timeframe. This tactic slows down attackers, prevents quick password guessing, preserves system resources, and detects suspicious behavior.

Striking the right balance is key to maintaining security without inconveniencing legitimate users.

Use Captcha tests

Including Captcha tests on login pages can make automated brute force attacks more challenging.

Employ multi-factor authentication (MFA)

MFA requires users to provide two or more credentials to authenticate their identity, thus adding an extra layer of defense.

Invest in security

Regularly update and patch your systems. Consider investing in intrusion detection systems (IDS) and employing a robust firewall. A digital cyber attack simulation from CovertSwarm can also help identify vulnerabilities in your systems.


Are brute force attacks illegal?

Yes, brute force attacks are illegal. They involve unauthorized access to personal or proprietary data, which is a clear violation of privacy laws in most jurisdictions.

How common are brute force attacks?

Brute force attacks are a common cybersecurity threat. Their frequency underscores the importance of implementing robust security measures, such as complex passwords and multi-factor authentication.

What is a secret?

In cybersecurity, a secret refers to confidential or sensitive information that is intended to be known and accessed only by authorized individuals, systems, or processes. Secrets are critical components of security systems and are used to protect sensitive data, authenticate users, establish secure communication channels, and prevent unauthorized access to resources.

Examples of secrets in cybersecurity include passwords, cryptographic keys, API tokens, encryption keys, security certificates, and any other information that, if compromised, could lead to security breaches or unauthorized access.

Safeguarding secrets is essential to maintaining the integrity, confidentiality, and availability of digital systems and sensitive information.

What’s an encryption key?

An encryption key is a random string of bits used to scramble and unscramble data in the process of encryption and decryption. The encryption key is kept secret and only shared with entities authorized to decrypt the data. The complexity and length of the encryption key directly impact the security of the encrypted data. 

What are some examples of brute force attack tools?

Cybercriminals use a variety of tools for brute force attacks, including the following. 

  1. Aircrack-ng – this is a suite of tools designed to assess wifi network security. It can crack keys once enough data packets have been captured.
  2. John the Ripper – originally developed for UNIX systems, John the Ripper is a popular password-cracking tool used to detect weak UNIX passwords. Today, it’s used across various systems and platforms.
  3. L0phtCrack – known for its password auditing and recovery capabilities, L0phtCrack is used to test password strength and recover lost passwords on Windows platforms.
  4. Hashcat – Hashcat is a robust password recovery tool. It supports a vast array of algorithms and is known for its speed and efficiency in cracking passwords.
  5. DaveGrohl – a dedicated password cracker for Mac OS X, DaveGrohl supports multi-threading and distributed cracking. It can be used for both dictionary and brute force attacks.
  6. Ncrack – developed by the team that created the network scanning tool Nmap, Ncrack is designed to crack network authentications. It supports protocols like RDP, SSH, HTTP(S), SMB, POP3(S), VNC, FTP, and others.

It’s worth noting that while these tools can be used maliciously, they are also used by our ethical hackers to identify system vulnerabilities and enhance security.

What’s the best defense against brute force attacks?

The best defense against brute force attacks involves a combination of strong password policies, employing multi-factor authentication, vigilant monitoring for unusual login activities, and ongoing cybersecurity education.

How do you strengthen passwords against brute force attacks?

To safeguard against brute force attacks, it’s crucial to use strong, unique passwords. Here are some tips.

  • Make your password long. Experts recommend a minimum of 12 characters.
  • Use a mix of uppercase and lowercase letters, numbers, and special characters.
  • Avoid personal information or common words that might be easy to guess.
  • Consider using a password manager to generate and store complex passwords.
  • Regularly update your passwords.
  • Enable multi-factor authentication whenever possible.


Brute force attacks are a prevalent threat in our interconnected digital ecosystem, capable of causing significant harm to individuals and organizations alike. 

Implementing robust security practices, monitoring system activities vigilantly, and investing in proactive measures, such as a simulated digital cyber attack from CovertSwarm, can help strengthen your cyber defenses. To further secure your systems, consider our password strength testing service to ensure your passwords withstand brute force attempts.

Secure your defenses. Choose CovertSwarm. 

Partner with our expert Swarm of ethical hackers to ensure your cybersecurity stance keeps pace with organizational changes and ever more sophisticated attacks from bad actors. Contact us for more information about brute force attacks.